1. Field of the Invention
The present invention relates to an outboard motor that includes, in an engine compartment formed above a mount case joined to an upper end of an extension case, a V-type engine positioned so that the heads of left and right cylinder banks face rearward, the engine being supported on the mount case. An intake manifold communicates with intake ports of the respective banks, an auxiliary fuel tank for temporarily stores fuel that has been drawn up from a main fuel tank on a hull side by means of a primary fuel pump, the fuel in the auxiliary fuel tank being supplied to fuel injection valves of the respective cylinder banks by means of a secondary fuel pump, and surplus fuel discharged from the secondary fuel pump is returned to the auxiliary fuel tank.
2. Description of the Prior Art
Such an outboard motor is already known in, for example, Japanese Patent Application Laid-open No. 5-106527.
In the outboard motor disclosed in the above-mentioned application, since the intake manifold is disposed in front of the engine, and an auxiliary fuel tank is disposed in a hollow between the left and right cylinder banks, it is necessary to enlarge the engine compartment, in particular because of the intake manifold in front of the engine. Furthermore, since the auxiliary fuel tank disposed between the left and right banks is easily heated by the left and right banks, there is the defect that the amount of fuel vapor generated within the tank increases.
The present invention has been achieved in view of the above-mentioned circumstances, and it is an object of the present invention to provide an intake and fuel system arrangement structure in an outboard motor in which the intake manifold and an auxiliary fuel tank are reasonably arranged, thereby contributing to making the engine compartment compact and, moreover, making it difficult for the auxiliary fuel tank to receive heat from the left and right banks.
In order to achieve the above-mentioned object, in accordance with a first aspect of the present invention, there is proposed an intake and fuel system arrangement structure in an outboard motor that includes, in an engine compartment formed above a mount case joined to an upper end of an extension case, a V-type engine positioned so that heads of left and right cylinder banks face rearward, the engine being supported on the mount case. An intake manifold communicates with intake ports of the respective banks, and an auxiliary fuel tank temporarily stores fuel that has been drawn up from a main fuel tank on a hull side by means of a primary fuel pump, the fuel in the auxiliary fuel tank being supplied to fuel injection valves of the respective banks by means of a secondary fuel pump, and surplus fuel discharged from the secondary fuel pump, is returned to the auxiliary fuel tank. The intake manifold is disposed in a hollow or space between the left and right cylinder banks, and the auxiliary fuel tank is disposed in an auxiliary equipment installation space that is formed between the left and right banks and the upper face of the mount case.
In accordance with the first aspect of the present invention, since the intake manifold and the auxiliary fuel tank are disposed effectively using the hollow between the left and right cylinder banks and the auxiliary equipment installation space formed beneath the left and right banks, the capacity of the engine compartment housing the intake manifold and the auxiliary fuel tank together with the engine can be comparatively small, thereby achieving a compact engine compartment. Moreover, the auxiliary fuel tank positioned beneath the left and right banks receives little heat from the left and right banks, thereby minimizing the generation of fuel vapor.
Furthermore, in accordance with a second aspect of the present invention, there is proposed an intake and fuel system arrangement structure in an outboard motor wherein the secondary fuel pump is connected to a side face of the auxiliary fuel tank and the secondary fuel pump and the auxiliary fuel tank are supported in the mount case.
In accordance with the second aspect, since the auxiliary fuel tank and the secondary fuel pump are made into an assembly, their ease of handling can be improved and, moreover, the structure by which the assembly is supported in the mount case can be simplified. Furthermore, since the auxiliary fuel tank and the secondary fuel pump are not in contact with the left and right banks, it is possible to avoid the conduction of heat from the respective banks to the auxiliary fuel tank and the secondary fuel pump, thereby preventing the fuel therewithin from being overheated.